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Newsgroups: rec.motorcycles
Subject: rec.motorcycles FAQ of 93.02.01 (Part 4 of 6)
Message-ID: <35128.89.uupcb@chaos.lrk.ar.us>
From: dave.williams@chaos.lrk.ar.us (Dave Williams)
Date: 30 Jan 93 20:18:00 GMT
Reply-To: dave.williams@chaos.lrk.ar.us (Dave Williams)
Distribution: world
Organization: The Courts of Chaos * 501-985-0059 * Public Access Usenet
Lines: 208
=====================
Q: The front brakes on my bike make a buzzing noise. I've looked all
over and can't see any loose parts. What is it?
A: You probably have drilled or slotted rotors. The holes often make
a noise as they move past the pads. Some bikes have floating rotors
which can make intermittent noises. In either case it's nothing to
worry about.
Q: Are drilled or slotted rotors more efficient than solid rotors?
A: There are many different reasons rotors are drilled or slotted.
Sometimes the rotors are drilled to lighten them, though your weight
savings is probably negligible. Honda claims the discontinuities
help braking in the rain and provide an escape route for mud or
rust.
Fred Puhn's "Brake Handbook" says, "Some rotors have slots or holes
machined into their contact surfaces. These reduce hot-gas and dust
particle buildup between pad and rotor. Although fade caused by
gas buildup is less for a disc brake than for a drum brake, some
fade still occurs. This is more prevalent with large brake pads,
because the hot gas has a harder time escaping than with small pads.
Therefore, slots or holes have greater effect in racing, where pads
are large and temperatures are very high."
Newcomb & Spurr's "Braking of Road Vehicles", 1967, tells us the
mass of the rotor is the primary factor for preventing brake fade.
When the rotor mass has absorbed enough heat, the brake will fade.
Vented rotors and ducting schemes will cool the rotor faster, but
it takes time; in rapid repeated braking cycles vented rotors do
little better than solid ones.
Carroll Smith's "Prepare To Win", 1975, says "Lately you may have
seen discs with tangential slots milled in the friction surfaces
or holes drilled in a tangential pattern normal to the friction
surface. This is an effort to wipe the "fireband" or boundary
layer off the disc before it reaches the point of contact with
the pad and to provide the very hot particles of friction material
worn off with some place to go other than the operating area."
=====================
Q: I have a 1973 Kawasaki Z-1. My owner's manual says it should run
premium leaded fuel. Will it hurt the engine to run unleaded?
The local shop says they need to install hardened valve seats
for $400.
A: No. Your Kawasaki already *has* hardened valve seats. Engines with
aluminum cylinder heads must have seat inserts, as aluminum is not
a suitable seat material. Someone is trying to rip you off.
*** Lights:
Q: I've seen ads for light modulators that flash the headlight and
brake light. Are these really useful? Should I buy one?
A: In general, no. Many states and municipalities prohibit flashing
lights (other than turn signals) except on authorized emergency
vehicles. Check your local laws before you buy. Even if you're
legal at home you still might pick up a ticket elsewhere.
Flashing lights often infuriate cagers, who will then mess with
you. Generally, the cagers win.
The flashing is also *very* bad for halogen bulbs. Expect your
headlight life to be significantly decreased.
*** Personal Equipment:
Q: I'm considering the purchase of a new helmet. The one I have
doesn't feel too good for some reason, even though it's the right
size. How can I tell when a helmet fits right?
A: First off, helmet sizes are like shoe sizes - they're only a general
guideline. Don't expect a size 8 to be the same size from two
different manufacturers.
Every brand of helmet is shaped differently inside. Of each brand,
most models are also different. The only way to find a properly
fitting helmet is to cruise the local shops and start trying them
on. Try ALL of them on, not just the expensive or pretty ones.
Proper fit is more important than gaudy stripes or fancy
certification. A properly fitting DOT-rated helmet is safer than
a badly fitting Snell-rated helmet.
The helmet should fit snugly. It shouldn't clamp your ears like a
vise, perch on top of your head like a ferret wearing a coffee cup,
or try to cave in your forehead. It shouldn't have any loose areas
either. As long as the chin bar doesn't try to move your jaw back
to your ears you're OK; in some helmets you're not *supposed* to be
able to touch the chin bar.
Many newer-design helmets have extensive padding in the cheek
area. This padding can cause interference with glasses. You can
sometimes get the cloth liner loose and cut reliefs with a razor
blade. You can also pull the liner loose and add extra foam to
adjust the fit in any loose areas. It's not a good idea to try to
cut the styrofoam section away to adjust the fit - find a different
helmet.
Some people get upset at the idea of altering the fit of their
helmet. The decision is up to you.
=====================
Q: The wind and engine noise from my bike get to me after a while. Is
it safe to wear earplugs when I'm riding?
A: I've never had a problem. I keep a couple sets of cheap foam plugs
in my bike's storage compartment; when I expect a ride to last more
than half an hour or so I put them in. They lessen the noise a lot
without blocking out sirens or screeching brakes.
In some places it is legal to drive if you're deaf, but not if you
are wearing earplugs. Check your local laws.
=====================
Q: What's a good buy for a leather jacket?
A: ronen@gg.caltech.edu writes:
Things to look for in a leather jacket:
OVERALL SUMMARY:
- Thick leather is a must. This is what makes the difference
between a motorcycle jacket and a fashion jacket.
Protection:
- Thick leather: heavy motorcycle leather (not "fashion" weight)
3-3.5oz weight or ~1-1.3mm thickness
- Elbow pads
- Shoulder pads
Cut & Fit:
up your back or the sleeves sliding up and leaving a gap at
the wrist.
- Sleeves really long
- Back should feel a little "hunch-backed" when standing upright
(more important on sport bikes than cruisers)
- Try it sitting on the bike.
- Fits closely in the forearms (sleeves zippered)
- Down only to hips if you dislike bunching up that longer
touring gear does.
- Make sure to leave room inside the jacked for sweaters & such.
- Don't buy anything you haven't tried on [conflicts w/ later
suggestions for buying mail order]
Comfort/Convenience:
- Zipper front
- Flap behind zipper to keep out the cold
- High collar
- Snap-down collar to keep it from slapping your cheek/neck
- Vents (zippered) to let in air during summer; grommets at armpits
- Removable (zip out) lining
- Zippers at wrists to keep sleeves from sliding up (while you're
sliding down the road)
- Lower back support panel for when you fall down.
- Stiff leather won't flap in the wind.
- (Tie a leather thong through hole in zipper tab for easy zipping
w/gloves)
Durability:
- Full-grain hides are preferred for repeated abrasion resistance,
but split or top grain will probably work the first time you
fall down.
- Double-stitching
Where to buy cheap:
- Sears surplus outlet
- J.C. Whitney catalog
- Mail-order places (see ads in riding magazines)
- Pawn shops
- Check police stations for Highway Patrol officers wanting to
sell used gear.
(If calling used/pawn/surplus stores: Try to get as much info as
possible over the phone. Give your size, etc. Be sure to say
motorcycle jacket, otherwise they will say "Sure, come on over
we've a fur lined brown leather coat and a pair of disco leather
patch pants.")
Miscellaneous:
- [The MSF course I took emphasized comfort first, protection
second -- being uncomfortable increases the likelihood of an
accident, and it's most important to decrease that likelihood.
Next important is protection, so that if an accident does happen,
the damage is minimized. Discomfort includes too hot, too cold,
too wet, too dry.]
- Get a jacket you really like (off the bike too); if you're like
a lot of folks, you'll wear it all the time anyway.
- Don't worry about stiffness; some new jackets need to break in.
- Hein Gericke jackets have it all, if you're willing to pay the
price. Sometimes discounters may have them cheaper than most
dealerships.
(end of part 4)